Fuji Photo Film Company, Limited

Hitoshi Hagiwara

Hiroshi Matsumoto

Nobuyuki Kita

Tadao Toyama

A presensitized plate for use in making a lithographic printing plate comprises a substrate; a photosensitive layer and a mat layer whose projections have an average diameter of not more than 100 .mu.m, an average height of not more than 10 .mu.m and whose coated amount ranges from 5 to 200 mg/m.sup.2, the photosensitive layer and the mat layer being applied onto the upper surface of the substrate; and a coating layer of an organic polymeric compound having a glass transition point of not less than 20.degree. C. and a thickness ranging from 0.01 to 8.0 .mu.m, the coating layer being applied onto the back face of the substrate. The presensitized plate makes it possible to solve the problem of the formation of scratches and the adhesion of the photosensitive layer to the back face of the PS plate even when a large number of PS plates are transported and/or stored while putting them in piles without sandwiching the PS plate between interleaves. The coated layer applied to the back face of the PS plate is tough and shows good adhesion to the substrate and is not peeled off during handling, development processing and printing operations.

Presensitized plate for use in making lithographic printing plate

The present invention provides a method of treating photosensitive printing plate, which comprises subjecting a photosensitive lithographic plate to exposure, development and burning-in treatment, characterized in that an aqueous solution containing phytic acid and aminobenzenesulfonic acid is applied to the lithographic plate after the development but prior to the burning-in treatment and then the burning-in treatment is conducted in the presence of these compounds. According to the invention, there can be prepared a lithographic plate free from background stain and having an excellent ink-receptive property in its image-forming area.

Method of treating photosensitive printing plate

A developing solution for developing a light-sensitive lithographic plate having a o-quinonediazide compound-containing light-sensitive layer is disclosed. The developing solution is comprised of an aqueous solution containing alkali silicate and an alkali aqueous solution-soluble compound of a metal selected from the group consisting of Sn, Pb, Fe, Co and Ni. The developing solution provides excellent resolving power, has excellent development stability, processing capability and adaptability with respect to automatic developing machines.

Process for developing light-sensitive o-quinonediazide lithographic

A developer for a light-sensitive lithographic printing plate having an o-quinonediazide-containing light-sensitive layer is disclosed. The developer is comprised of an aqueous solution of an alkali silicate containing an organic boron compound. The organic boron compound is represented by the formula ##STR1## the substituents are defined within the specification. By utilizing the developer of the invention it is possible to provide excellent developing power, development stability, processability and preferred forming properties during development.

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Shizuoka, Japan

Hitoshi Hagiwara